Display the stock availability for all product types in WooCommerce archive pages

add_action( 'woocommerce_after_shop_loop_item', 'wc_loop_get_product_stock_availability_text', 10 );

function wc_loop_get_product_stock_availability_text() {

    global $wpdb, $product;

    // For variable products

    if( $product->is_type('variable') ) {

        // Get the stock quantity sum of all product variations (children)

        $stock_quantity = $wpdb->get_var("

            SELECT SUM(pm.meta_value) FROM {$wpdb->prefix}posts as p

            JOIN {$wpdb->prefix}postmeta as pm ON p.ID = pm.post_id

            WHERE p.post_type = 'product_variation'

            AND p.post_status = 'publish' AND p.post_parent = '".get_the_id()."'

            AND pm.meta_key = '_stock' AND pm.meta_value IS NOT NULL

        ");

        if ( $stock_quantity > 0 ) {

            echo '<p class="stock in-stock">'. sprintf( __("%s in stock", "woocommerce"), $stock_quantity ).'</p>';

        } else {

            if ( is_numeric($stock_quantity) )

                echo '<p class="stock out-of-stock">' . __("Out of stock", "woocommerce") . '</p>';

            else

                return;

        }

    }

    // Other products types

    else {

        echo wc_get_stock_html( $product );

    }

}